Carburetor for internal-combustion engines



Dec. 16, 1924. 1,519,773

' C. M. DYER CARBURETOR FOR INTERNAL COMBUSTION ENGINES ocoa tpa'tented Dec E6, 1924 rais n STATES PATENT Pris- CECIL MUNRO DYER, OF KEW, VICTORIA, AUSTRALIA.

CARBURETOR FOR INTERNAL-COMBUSTION ENGINES.

Application filed May 23, 1924. Serial No. 715,404.

Commonwealth of Australia, have inventednew and useful Improvements in or Relating to Carburetors for Internal-Combustion Engines, of which the following is a specification.

This invention relates to improvements in carburetors for internal combustion engines, and more particularly to carburetors of the side-float type and having a Venturi mixing tube and a compensator well.

The principal object for which the invention has been devised is to provide a carburetor of compact construction having a high degree of efliciency, which will function satisfactorily with any of the various commercial grades of hydrocarbon oils that are used as fuel in internal combustion engines.

A further object is the provision of a carburetor having'a well so arranged that the fuel therein is subjected to the heat of an exhaust heated jacketaround the mixing tube, and an arrangement whereby to thermostatically and automatically compensate the rate of fuel supply through the well for diiferences in carburetor temperature controlled by the expansion and contraction of the tubular nipple or nozzle of the main fuel jet.

' A still furtherobject is the provision of a carburetor of the type described having 'a duct leading to a slow-running or idling jet, which duct is located in the heated area and receives its fuel supply independently of the main fuel jet.

crease the velocity of the air stream past the main jet; an auxiliary air valve fitted to the upper end of the mixing chamber; and means for regulatin the heat of the heating jacket around the enturi mixing tube.

With these and other objects in view the invention consists of the features of construct1on, combination and arrangement hereinafter fully described and as set out in the claiming clauses.

Reference being had to the drawings Figure 1 1s a view in sectional elevation of a carburetor representative of my invention.

Figure 2 is a detail sectional view of the means for controlling or re lating the flow of exhaust gases that are diverted from the exhaust manifold to the jacket around the Venturi mixing tube.

Figure 3 is a sectional elevation of a choke tube furnished with a pipe connection to enable crankcase aspiration, or humidified air, or stove heated a1r from the exhaust manifold, or steam to be delivered to the mixing chamber Figure 4 is a view illustrating means for detachably fitting the choke tube in the Venture mixing tube.

Figure 5 is a sectional view taken on line 1-1 of F'igure 1 illustrating the auxiliary air valve fitted to theVenturfifiiiiiig tube.

In these views, 6 designates a float chamher and 7 a ball-float that is supported at the inner end of a lever 8 pivoted on a pin 9 secured within said chamber. The ballfioat provides greater buoyancy and more leverage for quick cut-off than are obtainable with toggle-weighted cylindrical floats. Theouter end 10 of said lever is bifurcated and engages a flan ed collar 11 on a needle valve 12. Said collar has a screw-threaded engagement'with the needle valve for the purpose of ready adjustment according to the grade ofhydro-carbon fuel that is used, and it is maintained in a set adjusted position by lock nuts 13.

The needle valve, which has a fiat. side 12 to permit free passage of fuel to the float chamber and at its upper end a knob 14 whereby it can be conveniently actuated for engine priming, is vertically slidable in a guide boss 15 that is cast integrally with the float chamber. threaded into the lower portion of said guide boss so as to be readily detachable for renewal.

The liquid fuel inits flow from the supply pipe passes through a filter 17 and then via the passage 18, valve seat 16 and port 19 into the float chamber 6, the supply being regulated by adjustment of said needle valve. .The filter is so arranged that it can be conveniently removed for cleansing or The valve seat 16 is screwclosure caps 21 and 22, and at its bottom it is provided with a tapped discharge opening having a. drain plug 23. This plug is con- -structed with an enlarged head 24, and it .is furnished with a finger-operating piece 25. Formed in the drain plug 23 is a T- shaped duct 26. When the plug 23 is screwed into the float chamber, the enlarged head 24 is raised clear of the discharge opening, thus permitting the float chamber to be drained of its contents through said T- shaped duct.

The construction of the plug is such that it cannot become detached from the float chamber without first removing the fingeroperating piece 25, and the enlarged head 24 of said plug is a ground fit in a seat formed about the discharge opening in said chamber, thereby effectively preventing leakage when in its normal closed position. a.

A jacket constructed in two sections 27 and 28 to facilitate its detachment for cleaning purposes provides a heating chamber 29 surrounding a Venturi tube 30, said chamber being heated by exhaust gases diverted from the exhaust -ma-nifold of the engine in the manner hereinafter explained. The jacket section 27 is cast integrally with the float chamber 6, and formed on its inner surface is a well 31 that communicates with the float chamber 6 through a port 32. This port 32, which is disposed at a relatively high level to provide freedom from water and sediment obstruction from the float chamber, is below the normal level of liquid in said float chamber, in order that fuel will be constantly supplied to said well and maintained at required level therein. Located within the heating jacket and depending within said well-is a slow-running duct 33, the lower end of which is below the level of liquid fuel in said well. This duct 33 is constructed of metal having high heat conductivity to assist in vaporization of the fuel at a critical point, i. e., low engine speeds, and it is held in position by a gland 34. The upper end of said duct is accommodated in a hole formed vertically in a boss 35 on the Venturi tube 30, and it leads into a small chamber 36. This chamber is provided with a jet 37 arranged to deliver the vaporized fuel, under regulation of a needle valve 38, into the Venturi tube 30 at a'point above the throttle valve 39. The throttle valve is formed with a V-shaped marginal slot 40 providing a passage through which the airpasses at high velocity to meet and intimately mix with the fuel passing through the slow-running jet 37 at low engine speeds. Said V-shaped slot causes a thorough mixing of the air and fuel in the chamber above the throttle valve.

The needle valve 38 is screw-threaded into a, locking nipple 41. This nipple isscrewed into the boss 35, and it has a tapering inner end 42 which is split to securely retain said needle valve in any set adjusted position.

Screwed into the waist of the Venturi tube 30 is a tubular nipple 43, which provides direct means of communication between the well 31 and the Venturi tube at its waist portion. This nipple cooperates with a needle-valve 44 to provide the main fuel jet, and it has its bore 45 of lesser diameter than that of the lower disposed port 32 in order that said well 31 will be charged with fuel under all engine running conditions. Said screw-threaded nipple is shouldered at 46 and has a fibre washer 47, whereby a'fluidtight and readily detachable joint is effected.

The tubular nipple 43 is formed of gunmetal having a copper content of from 80% to 85% or of other suitable metal possessing a greater coeflicient of expansion under heat influence than the material of the carburetor so as to function as a thermostatic controlvalve automatically regulating the admission of fuel that is partly vaporized by reason of the location of the well 31 within the heating chamber 29. The bore of said nipple is flared at its inner end to form a seat for said needle valve 44, and said nipple expands readily by reason of its sensitiveness to heat variations. The needle valve is set for example, at one turn, thus giving :01; tnnular opening between said needle valve and the valve seat of say .001 of an inch. When the carburetor becomes heated by the exhaust gases admitted into the chamber 29, the needle valve seat expands and in the longitudinal expansion it decreases said annular opening in a direct ratio to the amount of heat applied, thereby automatically'reducing the flow of fuel to the Venturi waist and eflecting economy of fuel consumption by following an established principle of carburetion viz, the colder the fuel the greater is the amount thereof that is required to be fed to the induced air to obtain complete carburetion. By utilizing thermostatic means in the manner described, regulation of fuel flow is effected automatically, thus obviating the introduction of complex mechanical devices for the purposes.

The needle-valve 44 having a milled head is adjustable in a tapped guide sleeve 48, which extends through the jacket section 28 and is screwed into the waist of the Venturi tube 30, being maintained in position by a locking nut 49. A gland nut 50 is screwed onto the outer end of said sleeve to lock the needle valve 44 in any desired set position.

Formed in that portion of the Venturi tube 30 that extends below the surrounding heating jacket 29 is a series of regularly spaced air inlet openings 51, which corre-- spond dimensionally and in arrangement with similar openings 52 provided in a sleeve valve 53. T1118 sleeve valve is furformed to accommodate screwed studs 58 that are secured to the inturned flange 59 at the bottom of the Venturi tube 30.

The choke tube conforms in configuration substantially to that of the interior surface of the waist and lower portions of the Venturi tube, and spaced therefrom to form an annular passage 60 between'the wall of the Venturi tube and choke tube for the passage of the air around the outside of thechoke tube and through the same.

Formed oppositely in the upper vertical portion of the choke tube are two U-shaped slots 61 to slidably accommodate the inner portion of the needle 44 and the nipple 4:3. The upper edge of said choke tube is tapered outwardly, as at 62, for the purpose of directing outwardly the air that passes upwards through said choke tube and becomes vapor-laden. Provided in the lower vertical portion of the choke tube are elongated ports 63, which are preferably arranged 1n an intermediate position relatively to four adjacent air inlets 51 formed in the lower portion of the Venturi tube 30.

A tapped hole 64 centrally in the base of the choke tube 55 adapts it for connection of a pipe 63 which extends to a source of primary heated or humidified air supply, or steam supply. D

The choke tube is inserted within the lower portion of the Venturi tube with the heads of the studs 58 passing through the enlarged portions of the keyhole slots 57 and the U-sh'aped slots 61 in the upper portion of the choke tube embracing the needle 4.4 and thenipple'43. With the flanges 56 and 59 of the choke and the Venturitubes in abutment, the choke tube is sllghtly turned to bring said studs 58 into the smaller ends of the key-hole slots, thus locking said choke tube in position. The choke tube in like manner can be readily detached for inspection or for replacement by another choke-tube of different dimensions as m'ay be required when tuning-up the carburetor.

Air that is induced through the main air intake openings 51, regulated by the sleeve valve 53, is divided by the lower end of the choke tube 55 into streams-approximately one-half passing through the elongated ports 6.3 into the interior of the choke tube and the other half into the passage 60 between said choke tube and the Venturi tube. Air passing upwardly through the choke tube mixes with the fuel that issues from the main jet 43, and the mixture is directed outwardly by the tapered wall 62 at the upper end of the choke tube. Air flowing through the passage 60 meets and mixes with the fuel laden air issuing from the choke tube. By this means a more homogeneous mixture is effected.

The form of choke tube described and illustrated makes provision for suficient air for starting when the main air intake is closed, thus avoiding the pumping of excess fuel into the engine cylinder.

The carburetor is equipped with an auxiliary air valve, that is manually operatedo F or this purpose, a boss 66 is formed on the upper end of'the Venturi tube 30 and is tapped to receive the screw-threaded end 67 of an auxiliary air valve, while a circular recess is formed in the interior surface of the Venturi tube at its upper end and is covered with a ring 68 havingperforations 69. There is thus formed an annular chamber 70 for the diffusion of the extra air above the throttle 39.

The auxiliary air valve is of the plunger type and comprises 'a cylindrical barrel 71, wherein is slidably mounted a solid piston 72 adapted to be operated by a wire 7 3 from the instrument board or other place convenient to the driver.

Formed in spiral fashion through the wall of the barrel 71 is an air inlet port 74 of tapering width whereby the piston in its movement will control its area and thus regulate the supply of air that is, or may be, required for correcting the fuel mixture according to varying atmospheric conditions.

Additional air inlets 75 that are formed in the barrel 71' are normally covered by the piston 72, but may be uncovered by the movement of the piston 72 under the control of the driver for the purpose of admitting full volume of air into the chamber 70 whic diffuses it into the Venturi tube above the throttle, whence it passes into the engine cylinders.

The heating chamber 29 is provided with an inlet pipe 76 and an outlet pipe 77-see.

Figures 1 and 2. Exhaust gases diverted from the exhaust manifold by a pipe 78 formed with a hole 79 are delivered into said inlet pipe 76, and are caused to circulate through said chamber 29, thereby ensuring vaporization of the fuel mixture in the Venturi tube 30 and transmitting'a desired degree of heat to the hydro-carbon fuel in the well 31. Passage of exhaust gases, as aforesaid, is controlled by a valve 80 for heat regulation. This valve, which is of the screwdown plunger type, is adjustable ina casing 81 that is formed on an extension of one section of a clamp 82 encircling said pipe 78.,

Formed in the bottom of the casing 81 is a seat 83 to snugly accommodate the lower end of the valve when it is desired to cut off the supply of exhaust gases for heating purposes. .The valve is adjusted by rotating its head 84, wherein are formed holes 85 to receive a lever, and it is maintained in required adiusted position by a lock-nut 86.

A carburetor, as described, having a chamber disposed around the Venturi tube heated by exhaust gases; the arrangement of the compensator well and the slow-running duct within the heated area; means whereby the heat from the exhaust can be conveniently regulated or shut off, at will;.

the arrangement according, to which the slow-running duct draws its supply of fuel independently of the main jet, and the various devices facilitating adjustment of the integers is adapted to function satisfactorily With any of the various commercial grades of hydro-carbon oils :7

Vhat I do claim is I. In a carburetor, a chamber arranged as a Venturi tube having air inlet openings in the lateral wall at one end and an outlet at the opposite end, a float chamber adjacent to said Venturi tube, a jet fitted into the wall and in communication with the float chamber above the normal liquid level therein,

a valve to regulate the area of the outlet of said jet, a sleeve valve operative to re ulate the area of the inlet openings of the enturi tube. and a choke tube detachably secured within the Venturi tube, said choke tube being substantially of the configuration of the waist and inlet portion o'f,the Venturi tube and arranged in spaced relationthereto and having ports in the lateral wall in line with the inlet openings in the Venturi tube to admit a portion of air that is induced to flow through the inlet openings of the Venturi tube to flow through the choke tube and a portion between said choke tube and the Venturi tube.

2. A carburetor as claimed in claim 1 wherein the choke tube extends beyond the waist of the Venturi tube and has said end tapered outwardly and slotted to accommodate the main fuel jet and control valve for said jet, and the opposite end arranged for the'connection of a pipe for the purpose specified.

In testimony whereof I aflix my signature in presence of two witnesses.

, CECIL MUNRO DYE'R. Witnesses JAMES H. ANDERSON, LUCY M. GREEN. 

